Jolyon Jenkins concludes a series which investigates the changing face of epidemiology by looking at the relationship between communities, epidemiologists, public authorities and governments as they look for evidence of increased risk. Findings are likely to be contradictory, and for every study showing an effect, there will be one showing none. Each side seizes on the one that supports its case and in the middle are the public. Rescheduled from last week. Producer Paul Arnold. E-MAIL: scirad@bbc.co.uk